Today I talked with the owner of that revolving carbine, and he said it is marked "Uberti" on the barrel. But it's still strange that I've never seen a top strap receiver mounted adjustable rear sight like that on any other Uberti revolving carbine.
"This is my Remy and this is my Colt. Remy loads easy and topstrap strong, Colt balances better and never feels wrong. A repro black powder revolver gun, they smoke and shoot lead and give me much fun. I can't figure out which one I like better, they're both fine revolvers that fit in my leather".
"To be sure of hitting the target, shoot first and call whatever you hit the target".